find_package (Doxygen REQUIRED)

set (DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile)
set (DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)

configure_file (${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)
add_custom_target (docs
    COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
    COMMENT "Generating API documentation with Doxygen"
    VERBATIM)